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Houseplant care glossary
Plain-language definitions of the houseplant care words you'll meet in our plant profiles, guides and tools.
- terms
- 19
- Aerial root
- A root that grows from the stem above the soil. Climbing plants such as monstera and pothos use them to cling to supports.
- Bright indirect light
- Plenty of daylight without the sun's rays falling directly on the leaves, for example a spot a few feet back from a sunny window or behind a sheer curtain. Check your light with the light finder
- Chlorosis
- Yellowing of leaf tissue because the leaf is not making enough chlorophyll. Common causes include overwatering, root damage and a lack of nutrients such as nitrogen or iron. Why plant leaves turn yellow
- Dormancy
- A period of slowed or paused growth, often in winter when days are short. A resting plant needs less water and little or no fertilizer.
- Drainage hole
- An opening in the bottom of a pot that lets extra water run out, so the roots do not sit in water.
- Etiolation
- Pale, stretched growth with long gaps between the leaves, caused by too little light as the plant reaches towards a light source.
- Guttation
- Droplets of water that some plants push out at the leaf tips or edges, mostly at night or early morning when the soil is moist. It is a normal process, not a disease.
- Humidity
- The amount of water vapour in the air, usually given as relative humidity in percent. Many tropical houseplants prefer more humid air than a heated or air-conditioned home usually has.
- Leggy
- Describes a plant with long, bare stems and few leaves, usually from too little light or no pruning.
- Node
- The point on a stem where leaves, buds and aerial roots grow. Stem cuttings usually need at least one node to grow new roots and shoots. Propagation for beginners
- NPK (fertilizer)
- The three numbers on a fertilizer label, giving the share of nitrogen (N), phosphorus (P) and potassium (K). Nitrogen mainly feeds leafy growth, phosphorus roots and flowers, and potassium overall plant health.
- Offset (pup)
- A small new plant that grows from the base or roots of a parent plant, as in aloe, snake plant and many succulents. Once it has roots of its own it can be separated and potted up.
- Perlite
- Lightweight white granules of volcanic glass that has been heated until it expands. Mixed into potting mix, it improves drainage and lets air reach the roots. Build a mix with the soil mix builder
- Potting mix
- A growing medium made for containers, usually based on peat, coir or compost with bark or perlite. It stays lighter and drains better in a pot than garden soil. Find a mix for your plant
- Propagation
- Growing new plants from an existing one, for example from stem or leaf cuttings, by division or from seed. Propagation guides
- Rhizome
- A thick stem that grows sideways at or just below the soil surface and sends out roots and shoots. Snake plants, calatheas and many ferns grow from rhizomes.
- Root-bound
- When roots fill the pot and circle around its inside, leaving little soil. Roots growing out of the drainage holes and water running straight through are common signs. How to repot a plant
- Root rot
- Decay of the roots, usually because the soil stays wet for too long and fungi or water molds take hold. Rotting roots turn brown or black and mushy and can no longer take up water. How to spot and treat root rot
- Variegation
- Patches, stripes or edges of a different colour, often white, cream or yellow, on leaves or stems. The pale parts have little or no chlorophyll, so variegated plants often need more light than all-green ones.